The present invention relates to an infrared ray sensor package, an infrared ray sensor module, and an electronic device.
In recent years, size reduction, functional enhancement, and cost reduction have been demanded in an infrared ray sensor package having a vacuum-sealed infrared ray sensor element or in an electronic device having such an infrared ray sensor package.
Generally, infrared ray sensor elements (infrared detection elements) include thermal infrared detectors and photonic infrared detectors. Thermal infrared detectors are inferior to photonic infrared detectors in tracking capability. However, thermal infrared detectors detect the quantity of heat in a relative manner and may thus need no cooling mechanism. Therefore, the structure of an infrared ray sensor element can be simplified, so that the cost of manufacturing an infrared ray sensor element can be reduced.
As a conventional thermal infrared ray sensor package having no cooling mechanism, there has been known an infrared ray sensor package 141 as illustrated in FIGS. 8A and 8B (see, e.g., U.S. Pat. No. 7,470,904).
As shown in FIGS. 8A and 8B, the conventional infrared ray sensor package 141 includes an infrared ray sensor element 121, a lower housing 111, an upper housing 112, metal patterns 154, 155, and 157 formed on the lower housing 111, an infrared ray transmission window 113 joined to the upper housing 112, a seal ring 156 connecting the lower housing 111 and the upper housing 112 to each other, contact pins 142 serving as external output terminals of the infrared ray sensor package, a getter 151, and Kovar blocks 153 provided on the lower housing 111. The lower housing 111 and the upper housing 112 form a container 120. The getter 151 is mounted on the Kovar blocks 153.
In an infrared ray sensor package having a vacuum-sealed infrared ray sensor element, a trace amount of gas such as moisture, oxygen, and hydrogen is emitted from an inner surface of the package with time. Such emitted gas deteriorates the degree of vacuum after the vacuum sealing. In order to prevent this phenomenon, what is called a getter is provided within an infrared ray sensor package. The getter has a function of adsorbing the emitted gas (oxygen, carbon monoxide, moisture, carbon dioxide, nitrogen, hydrogen, and the like) to prevent deterioration of the degree of vacuum.
Generally, in order to maintain the gas adsorption capability of a getter, it is necessary to heat the getter at certain temperatures (about 400° C. to 500° C. at maximum). However, the infrared ray sensor element 121 is located adjacent to the getter 151 in the conventional infrared ray sensor package 141. Therefore, heat radiated from the getter 151 is transferred to the infrared ray sensor element 121 when the getter 151 is heated. Thus, the characteristics of the infrared ray sensor element 121 are problematically deteriorated.